Title: The reaction of C2H radicals with C2H6: Absolute rate coefficient measurements for T=295-800 K, and quantum chemical study of the molecular mechanism
Authors: Ceursters, Benny
Nguyen, HMT
Nguyen, Minh Tho
Peeters, Jozef
Vereecken, Luc # ×
Issue Date: 1-Apr-2001
Publisher: Royal soc chemistry
Series Title: Physical Chemistry Chemical Physics vol:3 issue:15 pages:3070-3074
Abstract: The absolute rate coefficient of the title reaction was measured for the first time at elevated temperatures, using a pulsed laser photolysis/chemiluminescence (PLP/CL) technique. C2H radicals were generated by excimer laser photodissociation of acetylene at 193 nm, and pseudo-first-order decays of thermalised C2H were monitored in real-time using the CH(A(2)Delta -->X(2)Pi) chemiluminescence from the reaction of C2H with excess O-2 as an ethynyl probe. The rate coefficients, measured over the temperature range 295-779 K, exhibit a slight non-Arrhenius behaviour and can be represented by k(C2H+C2H6)(T)=1.19x10(-12) T0.54 +/-0.20 exp[(180 +/- 70) K/T] cm(3) molecule(-1) s(-1). Ab initio calculations were performed at the MP2 and CCSD(T) levels of theory to elucidate the molecular mechanism of the C2H+alkane reactions. It is concluded that direct H-abstraction, leading to C2H2+alkyl radical, has by far the lowest energy barrier, approximate to3 kJ mol(-1), whereas substitution and insertion reactions face barriers in excess of 100 kJ mol(-1) and are therefore not competitive.
ISSN: 1463-9076
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Quantum Chemistry and Physical Chemistry Section
× corresponding author
# (joint) last author

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